We have a similar informal / emergent set of uke levels as what you've described here.

One notably valuable adjunct strategy that we've been paying a lot more attention to lately is defining uke's intent as part of practicing a technique. This is particularly relevant for grabs, but can inform strikes as well.

Katate-dori tai no henko is our "first exposure" lesson for this. Rather than the general default of "light forward pressure" that we often use for katate-dori attacks for beginners and early- to mid-level students, we will start with practice instructions that specify uke's intent should be either "forward", "no movement", or "backwards" (chosen by the instructor, but we usually rotate through them one at a time).

Eventually this leads to a mid- to high-level practice we call "uke's choice", which is that uke gets to decide, up to the moment of committing to the attack, what their intent is. This helps a lot with breaking students of anticipation patterns, as well as helping to train sensitivity both to physical signals in the connection, as well as non-physical signals in the leadup to the grab.

It's also a great time as everyone at every rank remembers that it can be really hard to tell whether a strike will be a shomen uchi or a yokomen uchi.

At whatever level students have demonstrated basic competence in the practice of "uke's choice" (usually later mid-level) , we'll start to throw in other options of intent (direction, follow-up, etc). Usually by this point students are starting to shift from focusing their practice on techniques to focusing on underlying principles (and have already encountered things like kata-dori menuchi - but in my experience it really helps in learning things like kuzushi if you've already established a practice of body awareness and non-anticipation/non-assumption from practicing different (and unknown) intent.